Support the radial load
Cylindrical rollers distribute radial force through line contact. Select the internal design against the actual load spectrum, stiffness requirement and operating speed.
Precision bearings / Cylindrical roller bearings / NN series
ROCK · Precision radial support
NN Series.
Built around
your spindle.
Double row cylindrical roller bearings for rigid radial support in precision rotating assemblies. Define the fit, clearance and accuracy your application needs—with ROCK.
Double rowSeparable constructionRadial load support
Standard-model inquiries · Drawing-based customization · Sample evaluation
NN SERIES / PRODUCT VIEW01—03
2 roller rowsCompact radial support
NN30Dimension series featured below
1:12 taperK bore configuration
Luoyang, ChinaROCK manufacturing base
01 / The bearing concept
Radial rigidity.
Room for thermal movement.
Two rows of cylindrical rollers provide radial support within a compact envelope. The NN ring arrangement also permits relative axial displacement within the bearing’s permitted limits.
Separate the rings
The ribless outer ring can be separated from the inner ring and roller assembly, simplifying fitting and inspection. Keep the matched bearing components together.
Plan the axial location
NN bearings provide radial support; they are not a substitute for an axial locating bearing. Where thrust loads occur, design a separate axial support arrangement.
02 / Structure & function
A clear load path.
A deliberate ring design.
The NN design uses a ribbed inner ring to guide two rows of rollers and a ribless outer ring. Bore geometry and mounted clearance are central to installation.
Concept illustration only. Cage, detailed profiles and running clearances are omitted; not a manufacturing drawing.
NN versus NNU
NN has guiding ribs on the inner ring. NNU uses the opposite ring arrangement. Confirm the complete designation before selecting a replacement.
Cylindrical or tapered bore
A cylindrical bore requires the specified shaft fit. A tapered bore allows controlled clearance adjustment through axial movement on the mating taper. The common K configuration uses a 1:12 taper.
Mounted clearance matters
Interference fits and temperature differences change the operating clearance. Specify the target mounted condition and measurement procedure rather than relying on the unmounted clearance alone.
Accuracy is an application decision
Define radial runout, axial runout where applicable, and dimensional tolerances. ROCK’s broader precision-bearing capability includes multiple accuracy grades; confirm the grade available for your selected NN model.
03 / Model finder
Start with the envelope.
Search common NN30 base designations or filter by shaft diameter. Add a model to your inquiry, then define its bore, cage and accuracy requirements.
| Base model | Bore d / mm | Outside D / mm | Width B / mm | Next step |
|---|---|---|---|---|
| NN3005 | 25 | 47 | 16 | |
| NN3006 | 30 | 55 | 19 | |
| NN3007 | 35 | 62 | 20 | |
| NN3008 | 40 | 68 | 21 | |
| NN3009 | 45 | 75 | 23 | |
| NN3010 | 50 | 80 | 23 | |
| NN3011 | 55 | 90 | 26 | |
| NN3012 | 60 | 95 | 26 | |
| NN3013 | 65 | 100 | 26 | |
| NN3014 | 70 | 110 | 30 | |
| NN3015 | 75 | 115 | 30 | |
| NN3016 | 80 | 125 | 34 | |
| NN3017 | 85 | 130 | 34 | |
| NN3018 | 90 | 140 | 37 | |
| NN3019 | 95 | 145 | 37 | |
| NN3020 | 100 | 150 | 37 | |
| NN3021 | 105 | 160 | 41 | |
| NN3022 | 110 | 170 | 45 | |
| NN3024 | 120 | 180 | 46 | |
| NN3026 | 130 | 200 | 52 |
No matching model. Clear the filters or describe your required dimensions in the inquiry below.
Boundary dimensions are reference values for common NN30 models, not a stock or interchangeability guarantee. Confirm the ROCK drawing before ordering. Load ratings, limiting speeds, chamfers and shoulder dimensions depend on the exact design and are supplied with the selected specification.
04 / Read the designation
Know what you
are specifying.
An example base designation: NN3022K. Select each element to see its meaning.
NN — Double row cylindrical roller bearing with guiding ribs on the inner ring.
Cage, lubrication, clearance and precision suffixes vary by manufacturer. SP, P4 and other codes should not be treated as universally equivalent. Send the complete existing designation for review.
05 / Application engineering
Choose for the whole assembly.
A bearing designation is only the starting point. Loads, fits, lubrication and thermal conditions determine whether a configuration is suitable.
Machine-tool spindles
Radial support where rigidity and rotational accuracy matter. Review the spindle arrangement, tool load, speed range and axial locating bearings.
Precision rotating shafts
Compact double-row support for engineered shaft systems. Check shaft deflection, housing alignment and thermal axial displacement.
Rebuild & replacement
Identify the complete existing code, mating dimensions and operating history. Matching d, D and B alone does not establish functional equivalence.
06 / Meet your manufacturing partner
ROCK.
Precision from Luoyang.
Luoyang Rock Precision Engineering Co., Ltd. manufactures precision bearings and supports drawing-based product development from Luoyang, Henan, China.
Our product scope includes cylindrical roller, angular contact, crossed roller, rotary table and thin-section bearings. For NN projects, we review your operating requirements and agree the product specification before production.
Inspection aligned to your drawing
Inspection scope may include material and heat treatment, hardness, dimensions, geometry, clearance, runout, surface condition and assembly quality. Agree the acceptance criteria and required records with your quotation.
Samples before a production decision
Sample evaluation can be arranged for initial and custom projects. Confirm the test plan, sample quantity and production approval requirements before committing to the batch.
07 / Installation & purchasing questions
Details that make the difference.
Can an NN bearing carry axial loads?
The NN arrangement is intended for radial support and allows axial movement between the rings within design limits. Use an appropriate locating bearing arrangement for axial loads. Provide both radial and axial loading when requesting a selection review.
How should a tapered-bore bearing be mounted?
Use the approved mounting procedure and specified clearance-reduction or displacement method. Measure the initial condition, control the advance on the taper and verify the final mounted condition. Do not use a universal drive-up distance or tightening torque across different sizes.
What should be checked before installation?
Check the identity and condition of the matched components, shaft and housing dimensions, cleanliness, shoulders and alignment. Apply mounting force through the ring being fitted rather than through the rollers. Verify lubrication and rotate the assembly by hand before a controlled run-in.
How is operating speed confirmed?
Permissible speed depends on internal design, cage, accuracy, load, clearance, lubrication and heat dissipation. A competitor’s catalogue speed is not a guaranteed speed for a ROCK bearing. Request the data for the exact configuration and operating conditions.
Can ROCK review a custom design or replacement code?
Yes. Supply a drawing or complete existing designation, installation envelope, operating loads and speed, precision and clearance requirements, lubricant, temperature and quantity. A technical review is needed before confirming the proposed configuration.
What are the sample, lead-time and inspection arrangements?
Sample evaluation and custom production can be discussed against your specification. Lead time depends on model, quantity and customization. Specify the inspection documents and packaging required in the inquiry so they can be agreed with the quotation.
08 / Your next step
Define the bearing.
Move the project forward.
Prepare a clear technical inquiry for ROCK. Start with a model or tell us about the assembly you are developing.
- Identify your model and quantity.
- Describe speed, loads, fits and lubrication.
- Include the drawing when sharing your inquiry.
The button prepares an email to Sales1@rockbearing.cn. Review and send it in your email app, adding your drawing as an attachment.